The launch of a satellite to monitor Earth's gravitational field, which had been postponed from September 10 to October 5, has been delayed for a second time, the European Space Agency (ESA) said on Thursday.
   
The one-tonne Gravity field and state-steady Ocean Circulation Explorer, or GOCE, now has a "tentative" launch date of October 27 at 1421 GMT, it said in a press release.
   
Launch preparations at the Plesetsk cosmodrome 800 kilometres (500 miles) north of Moscow have been hit by a problem in the guidance and navigation subsystem in the launcher's upper stage, called the Breeze KM.
   
"Russian launcher authorities are completing the investigation of the Breeze KM failure and implementing the related corrective measures," ESA said.
   
GOCE is part of ESA's "Earth Explorer" programme, initiated in 1999, to deepen understanding about some of the fundamentals of the planet -- its atmosphere, oceans, biosphere and interior.
   
GOCE's launcher is a Rockot, a derivative of a Russian intercontinental ballistic missile operated by a joint venture between EADS Astrium and the Khrunichev Space Centre.